By Pete Sansone
Part of being a crime scene investigator (CSI) is navigating the inherent and unique challenges you encounter. A crime scene is a living, breathing and fluid environment with numerous moving parts. Every scene demands answers to the following questions:
- What is the focus of the investigation?
- What are we trying to prove?
- What can we dispel or verify?
- And what does the evidence demonstrate?
The standard CSI processing model
Crime scene investigation is a 360-degree universe. What makes it unique is that no two scenes are ever the same. But whether the call is overwhelming or routine, the process we follow remains the same. It’s a universal language all CSIs speak — a standard we adhere to that ensures success at every scene. It’s also rooted in common sense and logic.
So what is this process I’m speaking of? It’s our standard scene processing model described by Ross Gardner Donna Krouskup in “Practical Crime Scene Processing and Investigation.” The model is as follows:
- Assess: This is the information-gathering phase — the briefing. Here you’re speaking with reporting officers, other investigators, victims, witnesses and sometimes suspects. During this phase, you should be sizing up the scene, ensuring your safety and its security. Do you have enough resources? If not, what else will be needed for successful scene resolution?
- Observe: Conduct a walkthrough with an officer or investigator. Continue to collect information. Visualize what’s being described to you. Verify or dispel the information you’ve been given. Based on what you’re seeing, could the incident have occurred the way it’s being described?
- Document: Use photographs, diagrams, drones, etc.
- Search: Look for supportive evidence. Once you are legally on scene, do your due diligence. Be sure to look everywhere and inspect everything. Everything that has the potential to be evidence is relevant until determined otherwise.
- Collect: Seize evidence. Determine what has the most probative value at the scene.
- Analyze: What are you going to do with the evidence? Are you going to process it? Are you going to send it to the lab? Are you returning it to the respective agency?
This standardized method makes it virtually impossible for anything critical to be missed or overlooked at a scene. It is cyclical in nature, flexible by design and court-defensible regarding exigent circumstances.
Once this model is applied, investigators turn to the Linkage Triangle to answer key questions at a scene. The Linkage Triangle connects the suspect, victim and the scene through evidence. There are four questions investigators should answer regarding evidence:
- What is it?
- What function did it serve?
- What relationship does it have to any other items?
- What does it tell us about time and sequencing?
Initial concerns at every scene — specifically preservation of life, scene safety and scene security — should come first before any processing begins. Keep in mind that everything within the scene has some degree of relevancy until it’s determined otherwise. We only get one opportunity to process any scene. Evidence can be transient, fragile and perishable, and should be prioritized during the initial assessment.
One of the most important things we can do as CSIs is remember the rule of chronology. As an investigator, you want to formalize your event sequencing (imaging) to facilitate event comprehension for the viewer. In short, you should be able to take all your scene photos and evidence and present them to the average layperson. If you have adhered to proper sequencing, that person should be able to look at the images and understand what happened, how it happened and in what order.
Use the right tools for the task
Don’t be afraid to use alternative processing techniques to achieve critical investigative tasks. Some examples might include magnetic fingerprint powder versus standard powder, impression casting in addition to digital imaging, or chemical enhancement versus ALS. As a CSI, you should be confident and capable in your ability to apply these techniques with the end goal of a successful judicial presentation. A picture is worth a thousand words — it provides perspective and ties event components together within a scene. However, we should always be mindful of identifying, documenting and recovering the most probative pieces of evidence.
These tasks are tedious, time-consuming, and exhausting. It isn’t the most glamorous investigative function. You will be subjected to scene hazards, environmental hazards, and personal and administrative pressures to expedite scene release. But fast doesn’t equal thorough. At the end of the day, this is your scene and your investigation, with the goal of being a voice for the victim. Let your investigative abilities, skill sets, integrity, and empathy be your guide.
About the author
Pete Sansone is a 25-year veteran of law enforcement who spent the last decade of his career as a Crime Scene Investigator. Pete is currently a board-certified CSI through the International Association for Identification. He is a retired St. Charles City (Missouri) Police officer currently working as a full-time CSI for the Illinois State Police.
| WATCH: A day in the life of a digital forensic examiner